1. Field of the Invention
The present invention relates to an arrangement for mounting a proximity mounting member relative to a “proximity” object with a predetermined distance therebetween.
2. Description of Related Art
As known, an electronic photographic image forming apparatus such as a copier, a printer, a telefax, includes an image fixing section having a fixing roller incorporating an electric driven fixing heater and a thermostat operable to stop power supply to the fixing heater upon detection of abnormal heat-up of this roller, the thermostat having a temperature detecting portion for detecting the fixing roller temperature. The temperature detecting portion of the thermostat is spaced from an outer peripheral surface of the fixing roller for a predetermined distance so as not to damage this roller. The thermostat per se is mounted to e.g. a supporting frame of the fixing roller. With this arrangement, the thermostat can detect a temperature of atmosphere adjacent the outer peripheral surface of the fixing roller as the fixing roller temperature, in a non-contact manner.
Next, as an example of “member mounting arrangement” to which the invention pertains, there will be described the arrangement provided in the fixing section of the image forming apparatus described above for mounting the thermostat, as an example of “proximity mounting member”, to the fixing roller, as an example of “proximity object” in such a manner that the temperature detecting portion of the former may be spaced apart from the outer peripheral surface of the fixing roller for a predetermined distance.
With the image forming apparatus, it is desired that a rise time required for the temperature of the fixing roller to rise from the normal (room) temperature to the image fixing temperature be as short as possible. It is also desired that the thermostat be mounted in close proximity of the fixing roller so as to allow the detection of the fixing roller temperature to be made with good responsiveness in a short period to the rise time.
With the conventional thermostat mounting arrangement in general, there is provided a housing having a cylindrical receiving portion for accommodating the thermostat therein and the thermostat is screw-fixed, with opposed terminal portions provided at the right and left extreme ends of the thermostat being placed in contact with the top face of the cylindrical receiving portion. Further, the housing for the thermostat is screw-fixed to the machine (apparatus) body so as to keep the temperature detecting portion of the thermostat away from the outer peripheral surface of the fixing roller for a predetermined distance (see e.g. Japanese Patent Application Laid-Open No. 2003-15463).
Accordingly, in order to allow speedy and highly responsive detection of the fixing roller temperature by minimizing the predetermined separating distance from the temperature detecting portion to the outer peripheral surface of the fixing roller, it is necessary to mount the thermostat with considerable degree of precision. Otherwise, i.e. if the mounting precision of the fixing roller is not so high, it becomes difficult to mount the thermostat, with maintaining the predetermined distance from the temperature detecting portion from the outer peripheral surface of the fixing roller. Then, the thermostat can sometimes contact the fixing roller inadvertently, due to displacement and/or vibration associated with the rotation of the fixing roller.